Catheter and method for a stent delivery system

ABSTRACT

An apparatus and method for deploying one or more stents within a body lumen comprises a catheter (such as a dilatation catheter) having a detachable proximal portion. Detaching the proximal portion from the catheter shaft allows a substantially tubular sheath to be slidably received over the proximal end of the catheter shaft. The tubular sheath has one or more substantially tubular stents positioned in a delivery configuration over a distal portion of the sheath. The sheath preferably has a proximal portion that is resistant to compressive forces, so that a user may advance the sheath along the catheter by pushing the sheath proximal end, thereby positioning the stent or stents at a desired deployment location within the body lumen. With the stents in position, the catheter proximal portion can be attached to the catheter shaft, and the stents can be deployed at the desired position. After the stents have been deployed, the catheter proximal hub can be removed, the first sheath slidably removed from the catheter shaft, a second sheath (containing additional stents) slidably introduced over the catheter shaft, the catheter proximal hub reattached, and the additional stents deployed. Thus, multiple stents can be deployed without necessitating removal of the catheter shaft until the procedure is completed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to stent delivery systems, which are used toimplant a stent into a patient's body lumen to maintain the patencythereof. More particularly, the present invention relates to a catheterhaving a removable proximal hub to allow a stent delivery sheath to beloaded and unloaded from the catheter without necessitating thewithdrawal of the catheter from the patient.

2. Description of Related Art

Stents are generally cylindrically-shaped devices which function to holdopen and sometimes expand a segment of a blood vessel or other bodylumen. They are particularly suitable for use to support and hold back adissected arterial lining which can occlude the fluid passageway. Stentsalso are useful in maintaining the patency of a body lumen, such as acoronary artery, after a percutaneous transluminal coronary angioplasty(PTCA) procedure or an atherectomy procedure to open a stenosed area ofthe artery. Several interventional treatment modalities are presentlyused for heart disease, including balloon and laser angioplasty,atherectomy, and bypass surgery.

In typical balloon angioplasty procedures, a guiding catheter having apreformed distal tip is percutaneously introduced through the femoralartery into the cardiovascular system of a patient in a conventionalSeldinger technique and advanced within the cardiovascular system untilthe distal tip of the guiding catheter is seated in the ostium of adesired coronary artery. A guidewire is positioned within an inner lumenof a dilatation catheter, and then both are advanced through the guidingcatheter to the distal end thereof. The guidewire is advanced out of thedistal end of the guiding catheter into the patient's coronaryvasculature until the distal end of the guidewire crosses a lesion to bedilated. Next, the dilatation catheter, having an inflatable balloon onthe distal portion thereof, is advanced into the patient's coronaryanatomy over the previously-introduced guidewire until the balloon ofthe dilation catheter is properly positioned across the lesion. Once inposition across the lesion, the balloon, which is typically made ofrelatively inelastic materials, is inflated to a predetermined size withliquid at relatively high pressure (e.g., greater than 4 atmospheres) tocompress the arteriosclerotic plaque of the lesion against the inside ofthe artery wall and to otherwise expand the inner lumen of the artery.The dilatation balloon is then deflated so that blood flow can beresumed through the dilated artery and the dilation catheter can beremoved. Further details of dilation catheters, guidewires, and devicesassociated therewith for angioplasty procedures can be found in U.S.Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185(Lindquist); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622(Samson, et al.); U.S. Pat. No. 4,554,929 (Samson, et al.); U.S. Pat.No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); and U.S. Pat.No. 4,748,982 (Horzewski, et al.) which are incorporated herein in theirentirety by reference thereto.

A major problem that can occur during balloon angioplasty procedures isthe formation of intimal flaps that can collapse and occlude the arterywhen the balloon is deflated at the end of the angioplasty procedure.Another major problem characteristic of balloon angioplasty proceduresis the large number of patients which are subject to restenosis in thetreated artery. In the case of restenosis, the treated artery may againbe subject to balloon angioplasty or to other treatments such as bypasssurgery, if additional balloon angioplasty procedures are not warranted.However, in the event of a partial or total occlusion of an arteryresulting from the collapse of a dissected arterial lining after thedilation balloon is deflated, the patient may require immediate medicalattention, particularly where the occlusion occurs in a coronary artery.

A major focus of recent development work in the treatment of heartdisease has been directed to endoprosthetic devices called stents.Stents are generally cylindrically-shaped intravascular devices that areplaced within a damaged artery to hold it open. Such devices can be usedto prevent restenosis or to tack up an intimal flap to maintain thepatency of the blood vessel immediately after intravascular treatmentssuch as PTCA.

Various means have been described to deliver and implant stents. Onemethod frequently described for delivering a stent to a desiredintraluminal location includes mounting the expandable stent on anexpandable member, such as a balloon, provided on the distal end of anintravascular catheter, advancing the catheter to the desired locationwithin the patient's body lumen, inflating the balloon on the catheterto expand the stent into a permanent expanded condition and thendeflating the balloon and removing the catheter.

However, the rapid and effective delivery of a stent to the desiredlocation within a patient's vasculature is difficult and time consuming,particularly where stent deployment is accompanied by a balloonangioplasty procedure or where multiple stents are deployed in the bodylumen.

It may therefore be important to improve existing stent delivery systemsto provide rapid stent delivery while at the same time allowing acardiologist to select a desired stent and catheter combination. Thepresent invention satisfies these needs.

SUMMARY OF THE INVENTION

The present invention is directed to an apparatus and method fordeploying one or more stents within a body lumen, without necessitatingremoval of the catheter from the body lumen prior to stent deployment.The invention generally comprises a stent deployment catheter having ashaft with a detachable proximal hub removably secured to a proximal endof the shaft.

In a preferred embodiment, the catheter shaft has an expandable memberat the shaft distal end. The detachable proximal hub may include acontrol device for controlling expansion of the expandable member. Thecatheter may also include a securing device that prevents rotation ofthe detachable proximal hub about the shaft axis when the proximal hubis secured to the shaft. Such a securing device may include one or moreprojections extending from the detachable proximal hub that areconfigured to be received in one or more apertures in the cathetershaft.

The stent deployment catheter may, in a preferred embodiment, comprise apart of a stent deployment system. Such a stent deployment systemgenerally comprises the aforementioned catheter with a shaft anddetachable proximal hub; a substantially tubular sheath configured toslidably move over the catheter shaft; and a substantially tubular stentpositioned over a distal portion of the sheath.

The substantially tubular sheath preferably has proximal and distalends, proximal and distal portions, an outer surface, and a lumentherethrough defining an inner surface. The sheath is configured forslidable movement over the catheter shaft. The distal portion of thesheath comprises a flexible, expandable material extending from theinner surface of the sheath to the outer surface of the sheath. Theproximal portion of the sheath is resistant to compressive forces.

The catheter preferably includes an expandable device, such as adilatation device or a balloon, at its distal end. The substantiallytubular stent is preferably a radially expandable stent having adelivery configuration and a deployed configuration. The stent ispositioned in the delivery configuration over the distal portion of thesheath.

In a preferred embodiment, the catheter is a dilatation catheter with anexpandable member at the catheter shaft distal end. The catheter may beintroduced into the body lumen such that the expandable member is at adesired treatment site, and the expandable member then expanded todilate the body lumen.

In one preferred method of operation, once the body lumen has beendilated by the dilatation device, the removable proximal hub canremoved, and the sheath can be longitudinally slid onto and over thesheath until the sheath distal portion bearing the stent is positionedover the expandable member. The expandable member can then be expanded.Because the sheath distal portion is formed of an elastomeric material,the sheath distal portion expands as the dilatation device expands. Thisexpansion of the dilatation device and sheath distal portion alsoexpands and deploys the stent at the desired location. The dilatationdevice can then be deflated, thereby causing the sheath distal portionto resume its unexpanded form. The stent retains its deployed, expandedform, and remains in the body lumen.

In another preferred method of operation, the removable proximal hub isremoved, and the sheath longitudinally slid onto and over the sheath,prior to dilatation of the body lumen. The sheath distal portion bearingthe stent is positioned just proximal of the expandable member. Becausethe stent is proximal of the expandable member, expansion of theexpandable member to dilate the body lumen will not cause the stent todeploy. After dilatation is performed, the sheath is advanced so thatthe sheath distal portion bearing the stent is positioned over theexpandable member. The expandable member is expanded, thereby expandingand deploying the stent at the treatment site.

In another embodiment, body lumen dilatation and stent deployment occuras a single step. In such an embodiment, the removable proximal hub isremoved, and the sheath longitudinally slid onto and over the sheathuntil the sheath distal portion bearing the stent is positioned over theexpandable member. The expandable member is then expanded, therebycausing the stent to expand and assume its deployed configuration.Expansion of the stent and expandable member also dilate the body lumen,so that stent deployment and dilatation of the body lumen occur as asingle step.

After the stent is deployed, the proximal hub can again be removed toallow the sheath to be slidably removed from the catheter shaft. A newsheath, bearing one or more additional stents, can then be slid onto thecatheter shaft and thereby introduced into the body lumen at a selectedsite. The proximal hub can then be reattached, and the new stent orstents deployed at desired locations. These steps can be repeated forseveral additional sheaths and stents, without requiring the catheter tobe withdrawn from the body lumen until deployment of all stents iscompleted.

The invention is applicable to various catheter designs, includingso-called over-the-wire (OTW) as well as rapid-exchange catheters.Examples of rapid-exchange catheters are shown and described in U.S.Pat. No. 5,180,368 (Garrison), U.S. Pat. No. 5,458,613 (Gharibadeh etal.), and U.S. Pat. No. 5,496,346 (Horzewski et al.).

Other features and advantages of the present invention will become moreapparent from the following detailed description of the invention whentaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, partially in section, depicting a deliverycatheter, sheath, and stent assembly according to the present invention.

FIG. 2 is a perspective view of a sheath according to the presentinvention.

FIG. 2a is a perspective view of an alternative embodiment of a sheathaccording to the present invention.

FIG. 3a is a perspective view of a stent in a delivery configuration.

FIG. 3b is a perspective view of the stent of FIG. 3a in a deployedconfiguration.

FIG. 4 is a perspective view of a sheath and stent assembly according tothe present invention.

FIG. 4a is a perspective view of a sheath and stent assembly accordingto an alternative embodiment of the present invention.

FIG. 5 is a perspective view, partially in section, of a deliverycatheter and sheath assembly used to deploy a stent in a human patientaccording to the present invention.

FIG. 6 is a perspective view of a delivery catheter according to theinvention.

FIG. 7 is a perspective view of the delivery catheter with thedilatation balloon expanded to dilate a body lumen.

FIG. 8 is a perspective view of the catheter of FIG. 7, with sheath andstent assembly, and with the proximal hub detached from the catheteraccording to a preferred embodiment of the current invention.

FIG. 9 is a perspective view depicting the delivery catheter of FIG. 6with a sheath and stent assembly, with the stent positioned fordeployment in the body lumen.

FIG. 10 is a perspective view depicting the delivery catheter, sheath,and stent assembly of FIG. 9 with the balloon expanded to deploy thestent in the body lumen.

FIG. 11a is a perspective view depicting a delivery catheter, sheath,and stent assembly with the balloon expanded to deploy a first stent ina body lumen.

FIG. 11b is a perspective view depicting a delivery catheter, sheath,and stent assembly of FIG. 11a, with the balloon expanded to deploy asecond stent in the body lumen.

FIG. 12 is an exploded perspective view of the proximal portion of acatheter according to a preferred embodiment of the current invention.

FIG. 13a is an exploded cross-sectional view of a proximal portion of adelivery catheter according to one embodiment of the invention.

FIG. 13b is a cross-sectional view of a proximal portion of the deliverycatheter of FIG. 13a.

FIG. 14 is a cross-sectional view of a proximal portion of a deliverycatheter according to an embodiment of the invention.

FIG. 15a is a cross-sectional view of a proximal portion of a deliverycatheter according to the invention.

FIG. 15b is a cross-sectional view of a proximal portion of a deliverycatheter according to a further embodiment of the invention.

FIG. 15c is a cross-sectional view of a proximal portion of a deliverycatheter according to a further embodiment of the invention.

FIG. 16a is a cross-sectional view of a proximal portion of a coaxialdelivery catheter according to the invention.

FIG. 16b is a cross-sectional view of a proximal portion of a dial-lumendelivery catheter according to a further embodiment of the invention.

FIG. 17 is a cross-sectional view of a proximal portion of a deliverycatheter according to the invention.

FIG. 18a is a perspective view of a proximal portion of a deliverycatheter and sheath used to deploy a stent in a patient.

FIG. 18b is a perspective view of the delivery catheter and sheath ofFIG. 18a.

FIG. 19 is a perspective view of a delivery catheter having an extendersection according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is depicted in FIGS. 1-19 for use in various bodylumens and procedures, including use in deploying stents in dilatedarteries during balloon angioplasties. However, the present invention isnot limited to use in blood vessels or angioplasties, but can be used inother body lumens and procedures to deploy stents, endovascular grafts,and similar devices.

Referring to FIG. 1, in one preferred embodiment the assembly 10 fordeploying a stent 12 comprises a balloon catheter 14. The ballooncatheter 14 comprises a removable proximal hub 16 having variouscontrols 18 located thereon, which is secured to a proximal end 19 of acatheter shaft 15. The catheter shaft 15 has a distal end 20 having adilatation device, which in the embodiment shown is a dilatation balloon22. In the embodiment shown, the balloon catheter shaft 15 has an innerlumen 24 that allows a guidewire 26 to pass therethrough.

The assembly 10 further comprises a sheath 28 having a distal end 30 anda proximal end 32. The sheath 28, which is shown in greater detail inFIG. 2, comprises two portions--a distal portion 34 and a proximalportion 36. The distal portion 34 preferably comprises an elastic,expandable material that can be expanded by outward pressure from withinthe sheath 28. The proximal portion 36 is preferably formed of amaterial that enhances the pushability of sheath 28 yet is flexibleenough to navigate the vascular system. The proximal portion length 40is typically several times the distal portion length 42.

The sheath 28 shown in FIG. 2 has an inner lumen 44 passing along thelength of the sheath 28. The sheath has an inner surface 46, defined bythe inner lumen 44, and an outer surface 48. The inner lumen 44 is sizedfor slidable movement over the dilatation balloon catheter shaft 15.

The sheath 28 of FIG. 2 has an outer diameter 50 sized to pass within abody lumen. The sheath 28 preferably has a length 52 that allows thesheath distal end 30 to be positioned at a desired treatment site in abody lumen while the sheath proximal end 32 is positioned outside of thebody lumen and patient, so that a user can manipulate the sheath 28 bygrasping and maneuvering the sheath proximal end 32. The precise sheathlength 52 will be determined by the particular application.

The sheath 28 may include a slit 47 extending from the sheath proximalend 32 toward the sheath distal end 30. The slit 47 allows the sheath tobe peeled apart to facilitate introduction or removal of variousdevices, such as a catheter or guidewire, via the side of the sheath.

FIG. 2a shows an alternative embodiment of a delivery sheath 28 having adistal portion 34 configured to receive a stent, but wherein most of theproximal portion is replaced by a mandrel 49. The mandrel 49 performsmuch as the proximal portion 36 described above with respect to FIG. 2.The mandrel 49 is preferably formed of a material such as a polymer,stainless steel, titanium, nickel-titanium alloy, fiber reinforcedpolymers, braided polymers, and braid reinforced polymers that enhancethe pushability of the sheath 28 yet is flexible enough to navigate thevascular system. The mandrel length 51 is typically several times thelength 42 of the distal portion 34. While the sheath proximal portion 36shown in FIG. 2 was configured to slidably pass over a catheter, themandrel 49 of FIG. 11 is configured to pass and lie alongside acatheter. The mandrel 49 may include a handle 53 by which a user cangrasp the device. Such an embodiment may be used with so-called rapidexchange catheters, and particularly with a rapid-exchange catheterhaving a removable proximal hub according to the current invention.

FIGS. 3a and 3b show an expandable stent 12 for use with the ballooncatheter 14 and sheath 28 of the current invention. The stent has aninner lumen 54 defining an inner surface 56, and an outer surface 58defining an outer diameter 60a. FIG. 3a shows the stent 12 in itsdelivery configuration, whereby the outer diameter 60a is small enoughto pass within a body lumen. FIG. 3b shows the stent 12 in its deployedconfiguration, whereby the outer diameter 60b is sized so that the stentouter surface 58 contacts the walls of the body lumen. The length 62 ofthe stent 12 is typically in the range of 5 to 50 mm, and preferablyabout 10 to 20 mm, but stents of almost any length may be used with theinvention, depending on the particular application. FIGS. 3a and 3b showa stent 12 of an open lattice configuration, similar to the stentdescribed in co-pending and commonly owned U.S. Ser. No. 08/454,599,which is incorporated herein by reference. However, other stent typesand configurations are well known in the art and also are compatiblewith the invention, so long as the stent defines an inner lumen and canbe partially or fully expanded with a dilatation device such as aballoon catheter.

FIG. 4 shows a stent and sheath assembly 64 for use with the currentinvention, with the sheath 28 similar to that previously described withrespect to FIG. 2. The stent 12 is positioned in its deliveryconfiguration on the sheath distal portion 34, with the stent innersurface 56 contacting the sheath outer surface 48. In the embodimentshown, the sheath distal portion length 42 is greater than the stentlength 62, so that the stent 12 can be mounted entirely on the sheathdistal portion 34 without contacting the sheath proximal portion 36.FIG. 4a shows an alternative embodiment of a stent and sheath assembly64a, wherein the sheath 28 comprises a distal portion 34 and a mandrel49, as was previously shown and described with respect to FIG. 2a.

The sheath and stent assembly are described in greater detail inconcurrently-filed U.S. Ser. No. 08/840,487, entitled SHEATH AND METHODFOR A STENT DELIVERY SYSTEM, with Jefferey Bleam and Andrew Mackenzie asinventors, which is incorporated herein by reference.

FIG. 5 shows the catheter, sheath, and stent assembly used in a balloonangioplasty procedure to deploy a stent 12 in a coronary artery 66 in apatient 68. The assembly has been percutaneously introduced through thefemoral artery 70 into the cardiovascular system of the patient 68, withthe dilatation balloon 22 positioned at a desired location to betreated. Both the catheter proximal hub 16, which includes the cathetercontrols 18, and the sheath proximal end 32 are positioned outside ofthe patient 68 so that a user may easily grasp and manipulate thecatheter 14 and sheath 28. The user may also remove the catheterproximal hub 16 from the catheter shaft proximal end 19 without havingto remove the catheter shaft 15 from the patient 68.

FIG. 6 shows a catheter according to the current invention. The ballooncatheter 14 includes a removable proximal hub 16 having various controls18 located thereon. The proximal hub 16 can be removably secured to aproximal end 19 of a catheter shaft 15. In a preferred embodiment, thecatheter shaft 15 has a distal end 20 having a dilatation device, whichin the embodiment shown is a dilatation balloon 22. In the embodimentshown in FIG. 6, the balloon catheter shaft 15 has an inner lumen 24that allows a guidewire 26 to pass therethrough.

Referring now to FIG. 7, the catheter is shown with the dilatationballoon 22 positioned within a body lumen 72 at a desired treatmentlocation 74, and the detachable proximal hub 16 positioned outside thepatient's body. The desired treatment location 74 may comprise blockage76, such as a stenosis caused by deposits of plaque, that partiallyoccludes the body lumen 72. With the dilatation balloon 22 positioned atthe desired treatment location 74, the dilatation balloon 22 isexpanded, thereby dilating the blockage 76 and body lumen 72. Withdilatation completed, the dilatation balloon 22 can be deflated.

FIG. 7 shows dilatation occurring without a sheath being present on thecatheter shaft, as where the dilatation catheter has been initiallyintroduced into the body lumen without a sheath. However, to reduce thesteps and time between body lumen dilatation and stent deployment, thesheath could be positioned on the catheter shaft during a dilatationprocedure, but with the distal portion bearing the stent kept proximalof the dilatation balloon. Moreover, the dilatation catheter shaft maybe initially introduced into the body lumen with or without the sheath.If the dilatation catheter shaft is initially introduced into the bodylumen without the sheath, the sheath can be subsequently introduced overthe catheter shaft by removing the detachable proximal hub, advancingthe sheath over the catheter shaft, and the reattaching the detachableproximal hub. The sheath can thus be introduced into the body lumenafter the catheter shaft has been introduced, and even after dilatationhas occurred.

In FIG. 8, the blockage 76 has been dilated and the dilatation balloon22 has been deflated. The detachable proximal hub 16 has been removedfrom the catheter shaft 15 to allow a sheath 28, including a selectedstent 12, to be slidably introduced and distally advanced over thecatheter shaft proximal end 19.

Referring now to FIG. 9, when the sheath proximal end 32 is distal(forward) of the shaft proximal end 19, the detachable proximal hub 16can be reattached to the catheter shaft 15. The sheath 28 is slidablyadvanced over the catheter 14 by maneuvering the sheath proximal end 32until the stent 12 is positioned over the dilatation balloon 22. Theslidable advancement of the sheath 28 may be achieved by the user, suchas a cardiologist, grasping the sheath proximal end 32 and pushing thesheath 28 forward (distally) along the catheter shaft 15. Because thesheath proximal portion 36 preferably consists of a generally stiffermaterial that is resistant to longitudinal compressive forces, the userpushing on the sheath proximal end 32 causes the sheath 28 to slide overthe catheter shaft 15 so that the distal portion of the sheath 34,including the stent 12, advances over the dilatation balloon 22.

After the catheter detachable proximal hub 16 has been reattached to thecatheter shaft 15 and the stent 12 has been positioned over theexpandable dilatation balloon, as shown in FIG. 10, the dilatationballoon 22 is expanded. The outward pressure from the dilatation balloon22 causes the sheath proximal portion 36 to expand outwardly, which inturn forces the stent 12 to expand outwardly until the stent assumes itsdeployed outer diameter 60b. In the deployed diameter, the stent outersurface 58 contacts and exerts some outward pressure against the walls82 of the body lumen 72, thereby preventing the walls 82, which may beweakened from the dilatation procedure, or the blockage 76, fromcollapsing inwardly and causing renewed blockage of the body lumen 72.

After the stent 12 is deployed, the detachable proximal hub 16 can beremoved from the catheter shaft proximal end 19, as was shown in FIG. 8.The sheath 28 can then be slidably removed proximally from the cathetershaft 15 by the user grasping and pulling the sheath proximal end 32, sothat the sheath 28 passes over the catheter shaft proximal end 19 whilethe catheter shaft 15 remains in place in the patient. Next, a newsheath with a new stent or stents can be loaded onto the catheter shaft,the detachable proximal hub can be reattached, the sheath slid forwarduntil the stent(s) is over the dilatation balloon, and the dilatationballoon expanded to deploy the stent(s). (In the alternative, new stentsmay be loaded onto the original sheath, and the "reloaded" originalsheath reintroduced over the catheter shaft 15 into the patient.) Thesesteps can be repeated to deploy multiple stents from multiple sheaths,without necessitating removal of the catheter shaft until the procedureis completed.

FIGS. 1, 4, and 8-10 show a single stent 12 mounted on the sheath 28.However, as described in concurrently-filed U.S. Ser. No. 08/840,487,entitled SHEATH AND METHOD FOR A STENT DELIVERY SYSTEM, anotherembodiment of a sheath compatible with the current invention involvesmultiple stents mounted on a single sheath. Thus, a single sheath may beused to deploy multiple stents in a body lumen during a singleprocedure, without the need for the sheath to be removed from the bodylumen until a plurality of stents have been deployed.

FIGS. 12a-12b show the catheter 14 used to deploy multiple stents in abody lumen during a single procedure, without the need for the cathetershaft 15 to be removed from the body lumen until the procedure iscompleted. In one method, the locations 74a, 74b to be treated may allbe dilated by the dilatation balloon 22 prior to deployment of any ofthe stents 12. After all locations to be treated have been dilated, thedeflated dilatation balloon 22 is positioned at the location 74a wherethe first stent 12a is to be deployed. The first sheath 28a is slidablyadvanced over the catheter shaft 15 until the first stent 12a ispositioned over the deflated dilatation balloon 22. Then the dilatationballoon is expanded, thereby deploying the first stent 12a as shown inFIG. 11a. The dilatation balloon 22 is then deflated. The detachableproximal hub 16 is removed from the catheter shaft 15, and the firstsheath 28a is removed from the catheter shaft 15.

The dilatation balloon is repositioned at the location 74b where asecond stent 12b is to be deployed. A new sheath 28b, including the newstent 12b, is slidably advanced over the catheter shaft 15 until thesheath proximal end 32a is distal of the catheter shaft proximal end 19.The detachable proximal hub 16 is reattached to the catheter shaft 15,and the second sheath 28b is distally advanced over the catheter shaft15 until the second stent 12b is positioned over the deflated dilatationballoon 22. The dilatation balloon is expanded to deploy the secondstent 12b, as shown in FIG. 11b. The procedure is repeated for anyfurther stents.

In another method, dilatation of selected treatment sights 74a, 74b mayoccur just prior to deployment of each stent, so that the first site 74ais dilated prior to deployment of the first stent 12a, followed byremoval of the first sheath 28a. The second site 74b is dilated afterdeployment of the first stent 12a and removal of the first sheath 28a,but before the introduction of the second sheath 28b and deployment ofthe second stent 12b, etc.

Various embodiments of securing the removable proximal hub to thecatheter shaft are applicable to the invention. For example, in theembodiment shown in FIG. 12, a catheter 14 has a proximal hub 16including several projections 86 extending distally from the distal end84 of the proximal hub. The shaft proximal end 19 includes correspondingapertures 88 sized and configured to slidably receive the proximal hubprojections 86. The apertures 88 may be formed through various methods,such as insert molding. When the proximal hub 16 is removably secured tothe shaft proximal end 19, the projections 86 lie within the apertures88, thereby preventing axial rotation of the detachable proximal hub 16about the catheter shaft 15. In another embodiment, projections may belocated on the shaft proximal end, with corresponding apertures locatedon the detachable proximal hub.

Another embodiment of the catheter is shown in FIG. 13a, wherein thedetachable proximal hub 16 has a base element 90 with a threaded element92 at its distal end 84. The proximal hub 16 also includes a nose cap 94configured to threadably receive the threaded element 92, and acompression fitting 96 positioned between the threaded element 92 andnose cap 94. The nose cap 94 and compression fitting 96 each has acentral bore 98 therethrough with an inner diameter 100 sized to receivethe catheter shaft proximal end outer diameter 102, as shown in FIG.13b.

When the nose cap 94 is threadably tightened onto the threaded element92, the compression fitting 96 presses inwardly against the cathetershaft 15. The compression fitting 96 may be formed of a compressiblematerial, such asurethane, rubber or any plastic material which recoversafter deforation, that also serves to create a seal about the cathetershaft proximal end 19 when compressed.

FIG. 14 illustrates another embodiment of the invention, wherein thecatheter has an inner member 104 and outer member 106, such as istypical of over-the-wire catheters. The catheter proximal hub 16 has aninner bore 98 therethrough, with a bore distal diameter 100a configuredto receive the catheter outer member 106 with a diameter 102a, and abore proximal diameter 100b configured to receive the catheter innermember 104 with a diameter 102b.

In the embodiment of FIG. 14, the base element 90 has a first threadedelement 92a configured to threadably receive a first nose cap 94a, witha first compression fitting 96a positioned between the first threadedelement 92a and first nose cap 94a. The base element 90 also has asecond threaded element 92b configured to threadably receive a secondnose cap 94b, with a second compression fitting 96b positioned betweenthe second threaded element 92b and second nose cap 94b.

In the embodiment of FIG. 14, the first threaded element 92a is locatedat the distal end 108 of the proximal hub base element 90, and thesecond threaded element 92b is located at the proximal end 110 of theproximal hub base element 90. The shaft inner member 104 extendsproximal of the shaft outer member 106.

With the catheter shaft inner member 104 positioned inside the secondcompression fitting 96b, the second nose cap 94b is threadably tightenedonto the second threaded element 92b, thereby compressing the secondcompression fitting 96b inwardly against the inner member 104. Thus, thesecond compression fitting 96b secures the inner member 104 while alsoproviding a seal about the inner member 104. Similarly, the cathetershaft outer member 106 is positioned inside the first compressionfitting 96a, the first nose cap 94a is threadably tightened onto thefirst threaded element 92a, and the first compression fitting 96apresses inwardly against the outer member 106.

FIG. 15a illustrates a further embodiment of the invention, wherein theproximal hub 16 is secured to the catheter shaft 15 via inwardly-facingprojections or barbs 112. The base element 90 of the proximal hub 16 hasa central bore 98 configured to receive the catheter shaft proximal end19. The inwardly-facing projections 112 are located inside the centralbore 98. The shaft may have corresponding apertures 114 sized to receivethe inwardly-facing projections 112.

When the catheter shaft proximal end 19 is slid into the base elementcentral bore 98, the inwardly-facing projections 112 engage against theouter surface 116 of the catheter shaft 15. Where correspondingapertures 114 are present on the catheter shaft 15, the inwardly-facingprojections 112 are positioned in the apertures 114, thereby securingthe proximal hub 16 to the catheter shaft 15.

The projections 112 may comprise one or more separate projections.Alternatively, the projections 112 may comprise a single, continuousannular ring about the central bore 98. The projections 112 may comprisea deformable material that compresses against the catheter shaft 15.Depending on the shape and configuration of the projections 112, theprojections may serve to seal the seam between the catheter shaft 15 andproximal hub 16.

As shown in FIG. 15b, the catheter 14 may also include a collar 118 thatstrengthens the connection and seal between the proximal hub 16 and thecatheter shaft 15. As shown in FIG. 16, the collar 118 may be located onthe base element 90 and, when slidably or rotatably advanced intoposition, compresses the central bore 98, which may include projections112, onto the catheter shaft 15. Alternatively, the collar 118 could belocated on the catheter shaft 15, such as where the catheter shaft 15fits around the distal end of the proximal hub 16 as shown in FIG. 16.

Various alternate configurations of projections and/or apertures may beused to secure the proximal hub 16 to the catheter shaft 15. Forexample, the catheter shaft 15 may be equipped with outward-facingprojections 120, as shown in FIG. 15c. These projections may align withand engage against inwardly-facing projections 112 and/or apertures 122in the proximal hub central bore 98.

FIG. 16a shows an alternative configuration of the invention, whereinthe catheter has an inner member 104 and outer member 106, such as istypical of over-the-wire catheters. The catheter proximal hub 16 has aninner bore 98 therethrough, with an inner bore distal diameter 100aconfigured to receive the catheter outer member 106 with a diameter102a, and an inner bore proximal diameter 100b configured to receive thecatheter inner member 104 with a diameter 102b. The central bore 98 hasa first set of projections 112a configured to engage the catheter shaftouter member 106, and a second set of projections 112b configured toengage the catheter shaft inner member 104.

FIG. 16a shows a catheter shaft having two coaxial members, i.e., andinner and an outer member. However, as shown in FIG. 16b, the cathetershaft may comprise two adjacent members 122, 124 in a side-by-sideconfiguration. In the embodiment of FIG. 16c, the first catheter member122 is an inflation lumen, and the second catheter member 124 is aguidewire lumen. The proximal hub 16 has two bores 126, 128. The firstbore 126 is sized to receive the first catheter member 122, and thesecond bore 128 is sized to receive the second catheter member 124.

FIG. 17a depicts a proximal hub 16 having a distal end 108 sized to bereceived within the catheter shaft inner lumen 130. The proximal hubdistal end 108 may have one or more outwardly-facing projections orbarbs 132. The projection 132 may comprise a single, continuous annularring about the proximal hub distal end 108.

When the proximal hub distal end 108 is inserted into the catheter shaftinner lumen 130, the projection 132 engages the catheter shaft innersurface 134, thereby securing the proximal hub 16 to the catheter shaft15. The projection 132 may also serve to seal the seam between thecatheter shaft 15 and proximal hub 16. The strength of the connectionand seal may be improved by having inwardly-facing apertures 136 and/orprojections 138 in the catheter inner surface 134. Where the catheterinner surface 134 has inwardly-facing projections 138, correspondingapertures 140 in the proximal hub distal end 108 may be used to enhancethe connection and seal.

Various techniques may be used to maintain the catheter shaft 15 inposition in the body lumen during the process of sliding a sheath 28over the catheter proximal end 19 and onto the catheter shaft 15. Forexample, the main catheter shaft 15 may have sufficient length that,with the dilatation device properly positioned at the deployment site inthe body lumen, the portion of catheter shaft that extends out of thepatient 68 is of sufficient length to entirely contain the sheath 28, asshown in FIG. 18a. Accordingly, as a sheath 28 is being advanced orremoved over the catheter shaft proximal end 19, a user can secure thecatheter shaft 15 in position via a securing section 142 of the cathetershaft that is distal of the sheath 28 but still outside of the patient68. As the sheath 28 is advanced into the body lumen and over thesecuring section 142, as shown in FIG. 18b, the user can secure thecatheter shaft 15 in position via the catheter shaft proximal end 19.Accordingly, the catheter shaft 15 is secured at all times, either atthe securing section 142 just outside the body lumen or via the cathetershaft proximal end 19, thereby preventing inadvertent movement of thedilatation balloon from the desired stent deployment location.

When the catheter embodiment of FIGS. 18a and 18b is used with a sheathembodiment such as that shown in FIG. 4, the catheter shaft 15 ispreferably two or more times as long as the sheath length. This allowsthe sheath 28 to be entirely removed from the patient 68 without anyportion of the sheath 28 passing over the catheter proximal end 19.

For the sheath embodiment shown in FIG. 4a, the catheter shaft onlyrequires a small length to be outside of the patient due to the shortlength of the forward "tubular" section of the sheath 28. Unlike theproximal portion 36 of the sheath shown in FIG. 4, the mandrel 49 of theembodiment shown in FIG. 4a does not surround the catheter shaft 15,instead lying alongside the catheter shaft 15. Accordingly, a user caneasily secure a section of the catheter shaft 15 even as the mandrel 49is advanced alongside that section.

Another embodiment is shown in FIG. 19, whereby the catheter 14 includesa removable extender section 144 having a length 146 similar to orgreater than the sheath length 52. The distal end 147 of the extendersection 144 is secured to the proximal end 19 of the main catheter shaft15. While resulting assembly of the catheter shaft 15 and extendersection 144 is secured in place by a user via the extender sectionproximal end 148, a sheath 28 can be slid from the extender section 144onto the main catheter shaft 15 and into proper position to deploy astent 12 at a desired location in the body lumen. After stentdeployment, a "depleted" (i.e., stentless) sheath can be slid from themain catheter shaft 15 onto the extender section 144. The extendersection 144, bearing the depleted sheath, can then be removed from themain catheter shaft 15 and either discarded or reloaded with a sheathbearing a stent. During removal and replacement of the extender section144, the catheter shaft 15 can be maintained in position via a proximalportion, such as the proximal end 19, of the main catheter shaft 15. Theextender section 144 may include controls 18 that control variousaspects of the catheter, such as controlling inflation of a dilatationballoon. The controls 18 may be located on a proximal hub 16 at theproximal end 148 of the extender section 144. The proximal hub 16 may beremovably secured to the extender section 144.

An extender section may be provided with a sheath and stent assemblypreloaded thereon, so that a user can select an extender section havinga desired sheath and stent assembly, secure the extender section to theproximal end of the catheter shaft, advance the sheath over the cathetershaft until the stent is positioned at the desired location in the bodylumen, and deploy the stent. The sheath can be then be slid off of themain catheter shaft and back onto the extender section. The extendersection can then be replaced with another preloaded extender sectioncontaining a sheath with a stent thereon. The process can be repeated todeploy several stents in the patient without requiring removal of themain catheter shaft from the patient until the procedure is completed.

The disclosed embodiments have described the sheath and stent assemblybeing used with a catheter having an inflatable balloon for deploymentof the stent. However, the invention is not limited to the use ofexpandable balloons. Other expandable devices for lumen dilatation andstent deployment are also compatible with the invention.

Although preferred and alternative embodiments of the invention havebeen described and illustrated, the invention is susceptible tomodifications and adaptations within the ability of those skilled in theart and without the exercise of inventive faculty. Thus, it should beunderstood that various changes in form, detail, and usage of thepresent invention may be made without departing from the spirit andscope of the invention. Accordingly, it is not intended that theinvention be limited, except as by the appended claims.

What is claimed is:
 1. A method for deploying one or more stents in a body lumen, the method comprising the steps of:(a) introducing a catheter shaft into a body lumen; (b) positioning a first stent about a distal end portion of a first tubular sheath, the first stent being configured in a delivery configuration; (c) slidably passing the first tubular sheath over a proximal end of the catheter shaft, thereby introducing the first tubular sheath into the body lumen; (d) positioning the first stent at a first desired location within the body lumen; (e) securing a detachable proximal hub to the proximal end of the catheter shaft; and (f) deploying the first stent at the first desired location, wherein said first stent assumes a deployed configuration.
 2. The method of claim 1, including, prior to step (c) but after step (a), the further step of:(g) removing a detachable proximal hub from a proximal end of the catheter shaft.
 3. The method of claim 1, wherein the catheter includes an expandable member at the catheter shaft distal end, and wherein step (a) comprises the further step of:(h) positioning the expandable member at the first desired position within the body lumen.
 4. The method of claim 3, wherein step (d) comprises the step of:(i) sliding the first tubular sheath over the catheter shaft until the first stent is positioned over the expandable member; and wherein step (f) includes the further step of: (j) expanding the expandable member to deploy the first stent.
 5. The method of claim 4, wherein the step of expanding the expandable member to deploy the first stent simultaneously dilates the body lumen.
 6. The method of claim 3, further comprising the step of:(k) dilating the body lumen with the expandable member.
 7. The method of claim 1, comprising, after step (f), the further steps of:(l) removing the detachable proximal hub from the catheter shaft; (m) slidably removing the first tubular sheath from the catheter shaft; (n) positioning a second stent about a distal end portion of a second tubular sheath, the second stent being configured in a delivery configuration; (o) slidably passing the second tubular sheath over the proximal end of the catheter shaft, thereby introducing the second tubular sheath into the body lumen; (p) positioning the second stent at a second desired location within the body lumen; (q) securing the detachable proximal hub to the proximal end of the catheter shaft; and (r) deploying the second stent at the second desired location, wherein said second stent assumes a deployed configuration.
 8. The method of claim 7, wherein steps (l) through (r) are repeated for additional sheaths and stents. 